Renewable Energy, Vol.91, 130-136, 2016
Experimental investigation on a MnCl2-CaCl2-NH3 thermal energy storage system
Thermal energy storage (TES) is regarded as one promising technology for renewable energy and waste heat recovery. Among TES technologies, sorption thermal energy storage (STES) has drawn burgeoning attention due to high energy storage density, long-term heat storage capability and flexible working modes. Originating from STES system, resorption thermal energy storage (RTES) system is established and investigated for recovering the heat in this paper. The system is mainly composed of three high temperature salt (HTS) unit beds; three low temperature salt (LTS) unit beds, valves and heat exchange pipes. Working pair of MnCl2 CaCl2 NH3 is selected for the RTES system. 4.8 kg and 3.9 kg MnCl2 and CaCl2 composite adsorbents are filled in the adsorption bed. Results indicate that the highest thermal storage density is about 1836 kJ/kg when the heat charging and discharging temperature is 155 degrees C and 55 degrees C, respectively. Volume density of heat storage ranges from 144 to 304 kWh/m(3). The highest ratio of latent heat to sensible heat is about 1.145 when the discharging temperature is 55 degrees C. The energy efficiency decreases from 97% to 73% when the discharging temperature increases from 55 to 75 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.